Hey Scott,
I did find 2 old 555s in the junk box and pulled a circuit from the internet (not any of the above).
Somehow I managed to blow up both while trying R and C values to get what I was after.
Went back to the relay method and just worked with that.
I tried to use the spare N/O contacts to drive the solenoid directly but the arcing meant the contacts wouldn't last too long. The solenoid draws a big pull-in current. And the spikes were crashing the apac.
Once I got the transister output working and suppressed all contacts the apac was happy.
I actually cheated on the transister circuit as I found a board in the junk that originally drove 4 solenoids, and had on board emf suppression so I hacked into that.
It's currently 'just right', other than the solenoid getting a little hotter than I'm comfortable with, hence the DC.
I seem to remember there was a simple RC network you could add accross a square wave to modify it's pattern but blown if I can remenber what it was called.
Oh to be 16 again!